Stoker control system



June 24, 1952 JUDSQN STOKER CONTROL SYSTEM 7 Sheets$heet 1 Filed Feb. 11, 1949 ALBERT L- JUDON TrU /VEW June 24, 1952 A. L. JUDSON 2,601,529

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Filed Feb. 11, 1949 l. 5 M U M 3 //\//E/\/ 727R ALBERT LJUDSOH HUN (Ill A. L. JUDSON STOKER CONTROL SYSTEM June 24, 1952 7 Sheets-Sheet 4 if? If.

Filed Feb. 11, 1949 MEAN-UR ALBERT w.- JUDSON fi TTUF A/i/ June 1952 A. L. JUDSON STOKER CONTROL SYSTEM 7 Sheets-Sheet'S Filed Feb. 11, 1949 [AH/EN TUR ALBERT 1.. JuDsoN June 24, 1952 A. 1.. JUDSON 2,601,529

STOKER CONTROL SYSTEM Filed Feb. 11, 1949 7 Sheets-Sheet 7 Patented June 24, 1952 UNITED STATES NT QFFICE STOKER CONTROL SYSTEM Albert L. Judson, Portland, reg., assignor to Iron Fireman Manufacturing Company, Fortland, Qreg.

6 Claims. 1

This invention relates generally to control systems for automatic coal stokers. More particularly this invention relates to the more effective types of stoker control systems in which a combustion gas temperature responsive instrument not only influences the re-fueling operation cycle of the system but which also provides an outfire shut down means which becomes effective if any operation of the stoker extends beyond a pre-determined time without attaining a pre-determined value of combustion gas temperature.

In the previous art a system of this general type would include a stoker relay and re-fueling timer in one instrument and a combustion gas temperature responsive means in another instrument separately mounted and electrically connected with the first instrument.

In the present system both these functions are combined into one stack mounted instrument whereby great simplification of circuits and mechanism are made possible and great economies in both controller construction and installation may be had.

It is, therefore, an object of this invention to provide a simplified stoker control system which yet accomplishes 'all of the desired functions found to be desirable in such a system.

'It is a second object to provide a system using a simplified master controller combining the functions of the stoker relay, re-fueling timer, and stack switch.

A third object is to provide a system in which the stack switchfunctional parts are in such proximity to the relay andtimer parts that the H stack switch may be mechanically effective to modify the operations of the relay and timer.

A fourth object is to" provide'such a system both economical to build and to install.

How these and othetobj'ec'ts are attained will be made clear by the following explanation and by reference to the attaghed drawings, in which:

F g. 1 is a general viewin perspective of the complete control.

Figs. 3, 3 t are schematic wiring diagrams of theelectr'ie control system including the control ofthis' invention together with the stoker e t h 'i19 l mstet the lim t control. and the outfire alarm lamp.

Fig. 2 represents the system in normal operating c rt ies Wlih th kle dl 3 we e i t e stem in orm l p a ing b sl iq g l th sta Operating du in a ii lin inter al;

F :F PI. the s st m abnorm lyut f 2 operating condition after the outfire switch has opened due to lack of temperature rise within the outfire time during a re-fueling period.

Fig. 5 is a rear elevation of the controller with the rear cover and the temperature responsive stem removed.

Fig. 6 is a section through the temperature responsive mechanism of the controller. The section line is shown by the'line 6- 6 of Fig. 5.

Fig. 7 is a front elevation of the mechanism of the controller.

Fig. 8 is a section along the line (i -E of Fig. 7.

Fig. 9 is a section along the line 9 30f- Fig. 7.

Fig. 10 is a section along the line "1710 of Fig. 7.

Fig. 11 is a section along the line H- -H of Fig. 7.

Fig. 12 is the same as Figure 11 but with solenoid switch closed and armature latched.

Fig. 13 is a perspective detail of the solenoid armature or solenoid switch pin actuator.

Fig. 14 is a fragmental front elevation of the controller showing the timing mechanism cover and the refuel cam in place over the mechanism 5 shown in the upper right hand corner of Fig. 7.

Figs. 15 to 18 show the mechanism shown in the upper right hand corner of Fig. 7 in progressive steps of operation.

Fig. 19 is a section along the line I9l9 of Fig. 7 with the refuel switch open, the refuel switch cam being in the position shown in Fig. 14.

Fig. 20 is a perspective detail of the refuel switch cam.

Fig. 21 is a perspective detail of the walking lever of the outfire timing switch mechanism.

Fig. 22 is a schematic drawing showing the construction and mode of operation of the described form of this invention.

Referring now to the drawing, there is shown a controller case having aremovable front cover 3| and a removable rear cover 32. Sheet metal terminal barrier 33"is spot welded to conduit terminal bracket 34 held to case "why screws 35. Thermostat wire entrance orifice 38 in bracket 34 has its perimeter smoothly rounded to prevent fraying of the thermostat wires.

Insulation sheet 3] is clamped to base 3i? by hollow-backed, molded, insulating terminal block 38 having its upper narrow base flange 3 ,9 slipped under clips 40 pressed forwardly out of base 33 a d y scr w 4| inserted throu h a hole in block 38 and threaded into base as. Recessed as shown into the front of block are thermostat terminals TI and T2, line terminal IDI, motor terminal I03, and ground terminal I02. Partially surrounded by raised barrier 42 on block 38 is alarm terminal I84.

Timing motor TM is secured to the rear of base 39 by screws 43. Transformer TR is secured to the rear of base 38 by screw 44. Wire 45 connects one side of coil of timing motor TM and one high voltage side of coil SI of transformer TR to ground terminal I82. Wire 49 connects the other lead of coil 5| and the other high voltage transformer lead to conducting bar 41 which in turn connects with terminal I84 and carries stationary contact 48 of solenoid switch SS and stationary contact 49 of outfire switch OS.

Solenoid switch frame 58 is secured to the front of base 39 and carries solenoid coil 1| and pivotally carries solenoid armature 52 on ears 53 and 54. Tension spring 55 hooked at one end over ear 56 of solenoid frame 58 and hooked at its other end over tongue 51 pressed forwardly from armature 52 biases armature 52 away from coil 1|, and through insulating pin 58 journalled in block 38 holds solenoid switch SS in open position when coil 1| is not energized. Spring blade 59 secured to terminal I83 and carrying movable contact 60 of switchSS biases switch SS to closed position.

Wires 62 and 63 from solenoid coil 1| connect respectively to thermostat terminal TI and one side of the low voltage coil of transformer TR. The other side of the low voltage'coil of transformer TR is connected by wire 64 to thermostat terminal T2.

Referring now to the combustion gas temperature responsive mechanism of the controller, heat responsive stainless steel tube 85 is welded to supporting flange 66 which in turn is secured to die casting 61 by screws 88 inserted through holes in flange 66 and threaded into holes 69 in casting 81. Casting 61 is secured to case 38 by screws 18. Porcelain tube 12 which has a very low temperature coeflicient of expansion is piloted at one end on the reduced diameter end of plug 13 welded into tube 65 and abuts plug 13. Plug 14 abuts tube 12 at its other end and has reduced end portion piloted in tube 12 and reduced end portion 16 protruding through a clearance hole in pipe cap 11 threaded onto tube -85 thus confining spring 18 and causing plug 14 to be moved toward or away from case 38 in accordance to a decrease or increase in the length of tube 65 due to the change in its temperature caused by the change in temperature of the combustion gases to which it may be exposed.

Spring 19 piloted on one end on boss 88 raised on the front surface of flange 65 has its other end confined by a depression in lever 8| fulcrumed on knife edge 82 secured to the rear of case 38. As shown in Fig. 6, spring 19 acting on one side of knife edge 82 causes lever 8| at all times to be pressed firmly against plug end 13 so that lever 8| at all times follows the movement of plug end 18 with respect to case 38. Cage wire 83 is merely an assembly aid and prevents lever 8| from leaving its location with respect to knife edge 82 when flange 65 with plug end 15 and spring 19 are removed. Dial headed screw 84 is threaded through lever 8| as shown. Latch lever 85 through ears 86 formed thereon and hinge pin 81 is pivotally carried on ears 88 formed on solenoid frame 58 secured to case 38. Screw 84 causes lever 85 to move about pin 81 with a motion equivalent to the motion of lever 8| about knife edge 82.

Latch 89 formed on lever 85 is positioned to engage armature 52 at a temperature of heat responsive tube 65 adjusted by dial screw 84. Thus when solenoid coil 1| is energized and armature 52 is attracted toward coil 1| and switch SS is allowed to close, then, if tube 95 is at or below the temperature determined by screw 84, lever will drop and latch 89 will prevent the opening of switch SS by armature 52 until the temperature of tube 85 has increased to the value preset by screw 84. Upwardly biased by spring 98, reset pin 9| guide-:1 in a clearance hole in casting 61, and protruding to the outside of case 38 through slot 92 formed therein, can be manually depressed to co-operatewith spring blade 93 secured to lever 85 to raise latch 89 out of its interference position with armature 52.

Pin 94 hinges rack arm 95 to bracket I89 secured to case 38 by screws 96. Index arrow 91 on bracket I89 co-operates with dial markings on screw 84 to indicate the temperature adjust ment position of latch 89 with'respect to armature 52. 7

Screw II3 adjustably threaded into rack arm 95 co-operates with latch lever 85 to hold rack 95 out of engagement with gear III whenever latch lever 85 is tipped up far enough for latch 89 to allow armature 52 to retract. Thus rack arm 95 can only engage gear III when coil 1| is energized and element 85 is below a predetermined temperature.

Roller 98 pivoted in spring clip 99 secured to armature 52 by screw H8 is positioned to contact the underside of arm 95 when latch 89 releases armature 52. As armature 52 pivots on ears 53 and 54 of frame 58 roller 98 tends to swing in an are about ears 53 and 54 taking its lowest position when coil 1| is energized and attracts armature 52 and its highest position when armature 52 is retracted by spring 55 after being released by coil 1| and latch 89. The effect of this upward motion of roller 98 is to give a quick upward shove to arm 95 and assure its complete freedom from gear III. This action of roller 98 makes unnecessary a close calibration of screw II3.

Pinion I I4 fixed to the output shaft of timing motor TM meshes with and drives gear I I5 fixed to cam shaft IIB journalled as shown in case 38 and gear frame II1 secured to case 38 by screw II8.

Walking lever II9 formed as shown in Fig. 21 has bearing holes I28 journalled on shaft IIB. Pivot pin |2| staked in hole I22 of lever II9 rotatably carries walking gear III always meshed with and driven by pinion I23 concentric with and fixed to shaft II6. Tension spring I24 hooked at one end to the extension of pin |2| and at the other to frame II1 biases walking lever H9 in a clockwise direction viewed from the front of the controller.

Cam arm I25 is rotatably mounted on shaft IIB. Aligned with arm I25 is latch plate I28 carried by frame II1. Pivot hook I21 of plate I26 engages the upper end of a slot formed in frame H1 and guide ear I28 freely rests in the bottom of the slot. Lobe I29 of arm I25 is normally positioned between lobe I38 and latch I3I of plate I28. Eye I32 is pressed laterally from arm I25 into alignment with hook I33 of lever II9. Spring I34 connects eye I32 with hook I33.

It is seen thatwhen rack 95 is disengaged from gear III, spring I24 urges lever H9 in a clockwise direction until it is stopped by striking frame II1. In this clockwise motion, the under side of foot I35 of lever II9 engages radial edge |32-A of arm I25 and carries arm I25 IH, an outfi-re switch timing period is startedwhich may be halted at any time the disenga ement of rack 95 with gear III or if the rack and gear are not disengaged will be carried through to, completion as shQWn in successive positio of the e em n i Figs, 16., 1.7 and 18. Starting with the idle pos tion shown in Fig. '7, in Fig. 15 gear III has advanced along rack 95 taking lever [I9 with it in a counterclockwise direction. Through sprin I34 lever H9 has moved arm I until lobe I29 has come into contact with latch I3 I of plate I25, In Fig. 16, it, is seen that the further motion of lever II9 merely extends spring I 34 until as seen in Fig. 17, foot I35 of; lever II!)v contacts the underside of lobe I30 of latch plate I26. With a further advance of gear II I as shown in Fig.,18,, foot :35. of lever H9 pushes on lobe I30 of plate I26 until latch I3I disengages lobe I29 of cam arm I25 and spring I34 suddenly advances arm I25 until stopped by eye I32 of arm I25 striking lever I I9.

Cam arm I25 is bent forwardly at its hooked end to form rearwardly sloping cam I36, the

outer end of which as shown in Figs. 9, '7, 15, r

16 and 17 is normally positioned over insulat-v ing pin I3! slidably positioned in a hole formed in terminal block 38. and resting against outfire switch blade I38 fixed at one end to terminal IM and carrying outfire switch contact, I39. As sloping cam I36 advances from the position shown in Fig. 17 to the position shown in Fig. 18, cam I36 depresses pin I3I which causes blade I38 to flex and separate outfire switch contacts 49 and I39, thus de-energizing the equipment and ending the outfire timing period.

Forwardly of frame III, spacer I40 is slipped over shaft H6 and gear cover MI is put in place and held by screws I42. Spring disk I43 is then slipped over shaft IIB, followed by cam disk I44 and both are held in place by nut I45 threaded onto the end of shaft 6. Cam disk I44 is thus frictionally adjustable in angular position on shaft IIB, but will normally be continuously rotating with shaft H6 in a counterhi clockwise direction.

Re-fueling switch RS comprises two spring blades I46 and I41, one end of each being secured respectively to thermostat terminals TI and T2, and carrying respectively switch contacts I48 and I49. The free end of each blade is inherently biased toward and bears against insulating pins I and I5'I respectively. Pins I50 and I 5| are slidably carried in vertically spaced holes formed in terminal block 38 and have their opposite ends each pressing one of the legs of horizontally U-shaped flat spring member I52 against the rearward side of the spiral cam faced periphery of disk I44. Member I52 is riveted to cover Ilil as shown in Fig. 14.

Disk I44 is slit radially for the width of the cam face and as installed thetrailing end of the cam is depressed rearwardly. In operation contacts I48 and because of the pressure of the cam face on blades I46 and I41 exerted through pins I50 and I5I. However, the respective lengths of the legs of member I52 are such that as the trailing end of the cam face of disk I44 comes to the posi- I49 are normally separated 6, tion of. pin 50 and 5! the log. oi mem e I52 whiohiboa s on s n oll.- wi r p o f the trailing end: of: he corn boiore th l h c bears on pin I54 and during the; Short space of time between the dropping off; of the respective legs contacts I48 and I40 of re-fueling switch RS will be closed.

To explain the operation of the stokersystem using this controller reference is made to Figs.

I 2, 3. and 4 showing simplified schematic elect e cont l e and he high r o ti w re H,

onnected to. te m nal "II of the co t oller- Lim trol 53 s shown s ri ith w re H- e st or m tor s connected b tw en terminal 0 nd l-3- he hermos at is conn ct d across rm nal TI and andan ou fire dicat ng amp L. or quiva nt de ice i o nected across terminals IOI and I04, it being d oo a th s d v ce. s. f; relatively hi h m edanc w th es ec to th windin s or the stoker mo r SlVL It i en thatthe sy tem is nergized throu h line imit. control 15.3.. m nal. IOI, and outfire sw ch OS. from w ich point parallel circuits are comp t d to t rmi al I02.- or line G in one case throu h the timin motor M. in another ase throu h the. primary coil of transformer and in the third case through solenoid switch con acts SS (when closed) and stoker motor SM.

The. low voltage. circuit includes the secondary winding of transformer TR, operating coil II of solenoid switch SS and, in parallel, the thermostat 'I and the resfueling switch RS.

As shown in Fig. 2, the. limit and outfire switches are. closed, the thermostat, re-fueling switch, and consequently the. solenoid switch are open and the timing motor and transformer are energized. Since switch SS is open the stoker motor is not operating. Fig. 2 thus illustrates a normal condition of the system when there is no call for heat but in which the controller is timing a fixed interval (one revolution of disk I44) to the next initiation of a rc-fueling period.

' Fig. 3 illustrates the condition of the system during a fixed part of a re-fueling period or for the time that the re-fueling switch is closed. It

is seen that coil II will be energized and therefore switch SS will be closed and the stoker motor SM will be operating. But here a particular feature of this controller not illustrated in the electrical diagrams comes into action. From the previous description of the mechanism of the controller it is remembered that whenever coil II is energized and switch SS is closed, latch 89 can drop to latch armature 52 and consequently switch SS in closed position unless combustion gas temperature responsive element 55 is above the predetermined temperature for which screw 84 has been adjusted. If element is above the selected temperature, lever I55v will not drop for latch 89 to engage armature 52 and after the short time (usually not over 30 seconds) required for disk I44 to advance enough to drop pin I 5| switch RS will open and the re-fuel period will be over. However, if element 65 is below the selected temperature, lever will be free to drop thus latching armature 52 and holding switch SS in closed position. Also when armature 52 i attracted to coil II and lever 85 drops, rack will drop also and engage gear I I I and thus initiate an outfire timing period. The refueling will thus be extended 7 beyond the period when the re-fueling switch is closed and will continue until the temperature of element 65 rises sufliciently to raise lever 85 and release armature 52 from latch 89. If this refueling period is extended without the temperature of element 65 rising the predetermined amount and continues for the outfire timing period (about 45 minutes) for which the controller is constructed theoutfire switch OS will be opened as previously explained and the entire system will be shut down.

Similarly to the cycle of operation just explained if the thermostat calls for heat by closing its contacts, switch SS will close to start the stoker motor, and if element 65 is below the predetermined temperature switch SS will be latched in and an outfire timing period started. Here also if the temperature of element 55 does not rise to the pre-determined temperature within the timed outfire period the system will be shut down by the opening of the outfire switch.

Fig. 4 indicates the electrical condition of the system after an operation had been initiated by the re-fueling switch but in which the combustion gas temperature did not rise sufiiciently in the outfire time and the system has gone to outfire. The re-fuel switch has opened (after only about 30 seconds of operation) but switch SS remains latched closed and after the outfire period has run out outfire switch OS has opened. High impedance signal device L now completes a circuit from wire H to terminal I94, through bar-.41, switch SS and the stoker motor to wire G. The small current passed by the signal device will not operate the stoker motor.

With attention thus called to the outfire condition of the system the difficulty can be overcome and then by manually depressing reset pin 9! extending through the top of case 38 the controller is reset to normal operating condition.

Having thus completely described the mechanism and operation of the control system of this invention and the primary controller which makes the system possible.

I claim:

1. An electric system for the control of an electrically operated stoker, comprising a source of electric power, an electric motor for driving said stoker, a first switching means operable to connect said motor to said power source, electrical operating means for said first switching means, a condition responsive second switching means operable to connect said operating means to said power source and to disconnect said operating means from said power source, a condition responsive lever means operable to latch said first switching means closed after said first switching means has been closed by said electrical operating means, a third switching means operable to disconnect said motor from said source of power, an aperiodic timing means operable to open said third switching means after having timed a definite time, means responsive jointly to said electrical operating means and said lever means operable to start said aperiodic means and to reset said aperiodic means in less than said definite time.

2. A controller for an electrically operated stoker, comprising a first line terminal, a second line terminal, said first and second line terminals being connected to an electric power source, a motor terminal, a stoker operating motor connected to said motor terminal and one of said line terminals, an alarm terminal, an alarm means connected to said alarm terminal and the other of said line terminals, a first thermostat terminal,

a second thermostat terminal, a thermostat connected to said thermostat terminals, a timing motor having an operating coil, a magnetic relay having an operating coil, an-armature, and a switch operated by said armature, a transformer having a primary winding and a secondary winding, an outfire switch, operating means for said outfire switch, a refueling switch, a condition responsive means, means connecting said first line terminal with one side of said outfire switch, means connecting the other side of said outfire switch with said alarm terminal, one side of said relay switch, one side of said primary coil of said transformer, and one side of said timing motor coil, means connecting said second line terminal with the other side of said primary coil of said transformer and the other side of said timing motor coil, means connecting said motor terminal with the other side of said relay switch, means connecting said first and second thermostat terminal in parallel with said refueling switch, and in series with said operating coil of said relay and said secondary coil of said transformer, means connecting said timing motor with said refueling switch, whereby said refueling switch will be periodically closed and opened when said timing motor coil i energized, means operable by said condition responsive means to couple said operating means with said timing motor when said relay operating coil is energized'and to latch said armature in its coil-energized position, if said condition is below a pre-determined value, and thereafter to unlatch said armature and uncouple said operating means if said condition rises above said pre-determined value, said means operable by said condition responsive means including means to couple said outfire switch operating means with said timing motor when said armature is in it coil-energized position and said condition is below said pre-determined value, whereby said outfire switch will be opened in a pre-set time if said condition does not rise to said pre-determined value and whereby if said condition rises to said predetermined value within said pre-set time said outfire switch operating means will be uncoupled from said timing motor and returned to its starting position.

3. A system for the control of an electric motor drive for a stoker, said system comprising a source of electric power, means for connecting said motor to said source of power, an operating means for said connecting means, means for periodically energizing said operating means for short intervals of time, and a condition responsive latch lever adapted to maintain said connecting means in its connected position to extend any of said intervals until said condition has attained a pre-set value.

4. In a system for the control of an electric motor drive for a stoker, said system comprising means for energizing said motor periodically for short intervals of time and means for extending each of said intervals until a pre-set combustion temperature is reached, the improvement which comprises a switch means operable to cause said motor to be energized, a condition responsive lever means adapted to latch said switch means in its motor energized position while said condition is below a pre-set value and adapted to release said switch means to its motor de-energized position when said pre-set value of said condition is reached.

5. In a system for the control of an electric motor drive for a stoker, said system comprising means for energizing said motor periodically for short intervals of time, means for extending each of said intervals until a pre-set combustion temperature is reached, and means for de-energizing said motor when any of said intervals reaches a pre-set length, the improvement which comprises a rockably pivoted toothed rack, a continuously running mating gear movable along said rack when engaged therewith, a condition responsive means adapted to eflect the engagement and disengagement of said rack and said gear, and means actuted by said gear in its movement along said rack to deenergize said motor if said movement proceeds to a pre-set position of said gear.

6. In a system for the control of an electric motor drive for a stoker, said system comprising means for energizing said motor periodically for short intervals of time, means for extending each of said intervals until a pre-set combustion temperature is reached, means for deenergizing said motor when any of said intervals reaches a preset length, automatic means for resetting said interval extending means whenever said pre-set combustion temperature is reached and manual means for resetting said interval extending means when any of said intervals reach said pre-set length, the improvement which comprises a first switch means operable to energize said motor, means for operating said first switch means, a condition responsive means, a pivoted lever having a latch thereon, means adapting said condi 10 tion responsive means to control said latch to engage said operating means when said operating means is in its motor energized position and said condition is below a pre-set value, a second switch means operable to de-energize said motor, a delay means for operating said second switch means, said delay means comprising a rockably pivoted tooth rack, a continuously running gear movable along said rack when engaged therewith, means adapting said rack to be controlled by said lever to engage said gear when said first switch operating means is engaged by said latch, and means actuated by said gear in its movement along said rack to operate said second switch means when said gear proceeds to a pre-set position.

' ALBERT L. JUDSON.

REFERENCES CITED The following references are of record in the file of this patent:

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